Magpul MBUS Rear Back-up Sight .223 Rear Sight, Black - MAG248-BLK.The Magpul MBUS Rear flip up sight is a durable color-injection molded folding back up sight. It conveniently folds down and locks into place but flips up with just a press of the button. Elevation adjustable, quickly mounts to any mil-spec 1913 Picatinny rail.
